Obstruction Removal System

ABSTRACT

An obstruction removal device is described, having one or more engaging members which can engage portions of the clot. The one or more engaging members have a collapsed, delivery state, and an expanded, deployed state which in some embodiments can be locked to maintain its fixed configuration.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/817,076 filed Nov. 17, 2017 entitled Obstruction Removal System,which claims benefit and priority to U.S. Provisional Application Ser.No. 62/426,106 filed Nov. 23, 2016 entitled Obstruction Removal System,which are hereby incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

The present invention relates to devices used to capture and removeobstructions, such as clots or other matter, from the vascular system,and the delivery of these devices to a target area within the vascularsystem.

The buildup of thrombi in vasculature can lead to formation of bloodclots. The formation of clots can result in restricted blood supply todownstream areas of the vasculature. When located in the neurovascularsystem, these clots can lead to stroke.

Recent technologies to remove clots utilize devices designed to hold andcapture the clot, followed by withdrawal of the device to physicallyremove the captured clots from the body. Several of these devices mayfail to capture the clot in its entirety or may promote clotfragmentation which may allow thrombi to dislodge and accumulate atanother site, thus continuing the risk of stroke. In addition, severalof these devices may promote endothelial denudation due to high frictionbetween the device and the vessel wall. Further, several of thesedevices collapse as they encounter a curve in the vessel, increasing thechance of allowing captured thrombi to escape and/or fragment.

There is need for an obstruction removal device which reduces thelikelihood of fragmented thrombi staying in the vasculature whilemaximizing the chance of mechanically capturing the clot, and limitingthe risk of endothelial denudation.

SUMMARY OF THE INVENTION

In one embodiment according to the present invention, an obstructionremoval device is described having a proximal axial core structure, adistal bumper structure and one or more engaging members mounted to thedistal bumper structure.

In another embodiment according to the present invention, an obstructionremoval device is described having a proximal structure, distalstructure, and one or more connected engaging members between the twostructures.

In another embodiment according to the present invention, an obstructionremoval device is described having a proximal structure, distalstructure, and one or more connected engaging members between the twostructures, where at least one of the engaging members acts as a filter.

In one example of the previously described embodiments, the pluralengaging members are substantially similar to each other.

In another example of the previously described embodiments, some of theplural engaging members are not substantially similar to the otherengaging members.

In another example of the previously described embodiments, some of theplural engaging members actively engage the clot while one or more ofthe remaining engaging members do not engage the clot.

In one embodiment, the obstruction removal device is sheathed within adelivery device and delivered through a catheter.

In another embodiment, the obstruction removal device is delivereddirectly through the catheter.

In another embodiment, the device is used to retrieve foreign objects.

In one embodiment, the obstruction removal device comprises a pluralityof obstruction engaging members linked together with individuallinkages. The linkages link a pair of engaging members together.

In one embodiment, the obstruction removal device includes a lockingmechanism to lock one or more engaging members in an expanded and/or acontracted shape. In one embodiment, device includes a hypotube pusherand a shape controller element which sits within the pusher and spansthe entire length of the one or more engaging elements, wherein theshape controller is used to contract and/or expand the engaging membersor hold the engaging members in a fixed or locked state.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which embodiments ofthe invention are capable of will be apparent and elucidated from thefollowing description of embodiments of the present invention, referencebeing made to the accompanying drawings, in which

FIG. 1 is an engaging member used in an obstruction removal device.

FIG. 2 is another view of the engaging member used in an obstructionremoval device.

FIG. 3 is an obstruction removal device according to one embodiment ofthe present invention.

FIG. 4 is an obstruction removal device according to another embodimentof the present invention.

FIG. 5 is an exploded view of the obstruction removal device shown inFIG. 4.

FIG. 6 is a magnified view of the proximal engaging member of theobstruction removal device of FIGS. 4 and 5.

FIG. 7 is an obstruction removal device according to another embodimentof the present invention.

FIG. 8 is an exploded view of the obstruction removal device shown inFIG. 7.

FIG. 9 is one of the distal engaging members used in the device shown inFIGS. 7 and 8.

FIG. 10 illustrates a method of deploying the obstruction removal devicedescribed in the previous embodiments.

FIG. 11 illustrates a method of deploying the obstruction removal devicedescribed in the previous embodiments.

FIG. 12 illustrates a method of deploying the obstruction removal devicedescribed in the previous embodiments.

FIG. 14 illustrates a process used to help set the final shape of anengaging member.

FIG. 15 illustrates a process used to help set the final shape of anengaging member.

FIG. 16 illustrates a process used to help set the final shape of anengaging member.

FIG. 17 illustrates an obstruction removal device utilizing hypotubesand a shape controller which allow the engaging members to adopt anexpanded and/or contracted shape.

FIG. 18 illustrates an obstruction removal device utilizing hypotubesand a shape controller which allow the engaging members to adopt anexpanded and/or contracted shape.

FIG. 19 illustrates an obstruction removal device utilizing hypotubesand a shape controller which allow the engaging members to adopt anexpanded and/or contracted shape.

FIG. 20 illustrates the hypotubes used in the obstruction removal deviceof FIGS. 17-19.

FIG. 21 illustrates the hypotubes used in the obstruction removal deviceof FIGS. 17-19.

FIG. 22a illustrates an obstruction removal device utilizing holderelements used to retain the struts of the engaging members used in theobstruction removal device.

FIG. 22b illustrates an obstruction removal device utilizing holderelements used to retain the struts of the engaging members used in theobstruction removal device.

FIG. 23 illustrates an obstruction removal device utilizing holderelements used to retain the struts of the engaging members used in theobstruction removal device.

FIG. 24a illustrates a locking mechanism for an obstruction removalsystem.

FIG. 24b illustrates the locking mechanism for the obstruction removalsystem of FIG. 24 a.

FIG. 25a illustrates a locking mechanism for an obstruction removalsystem.

FIG. 25b illustrates the locking mechanism for the obstruction removalsystem of FIG. 25 a.

DESCRIPTION OF EMBODIMENTS

Specific embodiments of the invention will now be described withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Theterminology used in the detailed description of the embodimentsillustrated in the accompanying drawings is not intended to be limitingof the invention. In the drawings, like numbers refer to like elements.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

For the purposes of the terminology described below, the terms clot,thrombus, embolus, and obstruction can be used synonymously. Though anobstruction removal device is described, the device can also be used tocapture clots, thrombi, emboli, foreign bodies, or other matter.Engaging members on the device can engage clots, thrombi, emboli,foreign bodies, obstructions, or other matter.

FIGS. 1 and 2 show an engaging member 100 used with the obstructionremoval device of the present invention. One or more engaging membersare used as part of an obstruction removal device in order to engagethrombus which can accumulate within a vascular system. General engagingmember shapes can include, but are not limited to, round, oval,elliptical, hourglass, spherical, basket, stent, countered, rectangular,prismatic, cage. Each engaging member 100 has a number of struts 101which define a number of cells, or openings 102, and a pair of opposingholes 103 and 104. For the sake of convention, hole 103 is a distal holeand hole 104 is a proximal hole.

Each engaging member may be uniquely configured with different struts,cells, cell sizes, materials, and/or shapes. The strut design can have alinear, wave, sinusoidal, or zig-zag pattern, or can have anon-symmetrical design (i.e. where struts on one side of the engagingmember are not mirrored on the other side of said engaging member). Thenon-symmetrical strut design may help facilitate a rotational componenton the member as it travels through a vessel, by shifting the center ofgravity from the geometric center of the engaging member. This ease ofrotation makes it easier for the engaging members, and therefore theobstruction removal device, to move more easily through the anatomy,especially after the clot has been engaged and the device is beingpulled back through the vasculature. This ease of rotation can alsolimit the amount of damage to the vessel wall due to excessive contactfriction by limiting the damage to a particular section of the wall. Theengaging members may have either identical or unique designs on each endof the engaging member. This may be done by varying shape of the strutsand/or cells, and/or varying the cell density of each end, thus—forexample allowing for large cell sizes on one end and smaller cell sizeson the opposing end. This variability may allow for different propertiesto allow for enhanced ability to engage the clot, or enhanced ability totrack the obstruction removal device and deployed engaging membersthrough the vessel.

FIG. 2 shows an engaging member 100 having a plurality of struts 101having different thicknesses. More specifically, a plurality of endstruts 101 a branch out from the material defining proximal hole 104,and one or more of these struts 101 a split to form struts 101 b. Struts101 b are shown with features 105 protruding therefrom. Features 105 maybe any interruption in the otherwise continuous surface of the strut101. Non-limiting examples include barbs, bumps, protrusions, spikes,branches, nubs, and the like. The struts 101 b are then shown as joiningan adjacent struts 101 b to form thicker struts 101 c, which then splitagain to form additional struts 101 d, also shown as having features105. These struts 101 d then join together again to form thicker struts101 e, which are connected to define distal hole 103. As such, it isseen that, in this particular embodiment, the struts interconnect toform a web of struts that span from the proximal hole 104 to the distalhole 103.

Another strut configuration could utilize a single strut pattern. Anexample includes a contiguous, helical strut configuration runningbetween the proximal and distal ends of the engaging member, or runningbetween a portion of the length spanning the proximal and distal ends ofthe engaging member.

Each engaging member has a collapsed configuration when sheathed withina delivery device, and takes on an expanded configuration as shown inFIGS. 1 and 2 when unsheathed. Each engaging member can beself-collapsible and self-expandable based on whether an external forceis applied to constrain it (as would be the case when sheathed in adelivery device), or no constraining force is present (as would be thecase when unsheathed).

The engaging member may be formed from nitinol, or a similar material,and may be laser cut to achieve the profile shape. Other materials andother cutting and/or machining processes would fit within the scope ofthe invention.

The distal and proximal holes, 103 and 104, on respective distal andproximal end of the engaging member, may facilitate placement of acommon rod on which each engaging member sits, or they may fit separateconnection pieces to connect multiple components of the obstructionremoval device with the respective engaging members.

FIG. 3 illustrates an obstruction removal device 200 according to oneembodiment of the present invention. The obstruction removal devicecomprises a proximal core structure 201 at one end of the device, adistal bumper structure 202 connected to the proximal core structure201, and one or more engaging members 203 mounted to the distal bumperstructure 202. In one example, the device is pushed and/or pulled fromthe core structure 201 end. A pusher may sit under the core structure,or the core structure itself may act as a pusher.

Core structure 201 may be made of a variety of materials, including, butnot limited to, nitinol, stainless steel, cobalt chromium, or apolymeric material such as PTFE, Pebax, TPE, Engage, polyethylene, orother similar materials. Core structure configurations can include, butare not limited to, a coil, a braid, or a coil/braid combination.

The bumper structure 202 may be made of a radiopaque material,including, but not limited to, platinum, tantalum, palladium, or othersimilar material. A radiopaque material is preferred to make imaging ofthe device easier during the device insertion procedure, althoughnon-radiopaque materials may also be used. The engaging members beingmounted to the bumper structure, where the bumper structure is made of aradiopaque material, aids in imaging the device during the clot removalprocedure. The engaging members may be mounted to the bumper structurein several ways. For example, the bumper structure may have a threadedouter profile, where the holes of the engaging members have acorresponding receiving structure to rotatably mate to the threadedbumper structure profile. Alternatively, the bumper structure may have anon-threaded outer configuration, and the engaging members may beaffixed to the bumper structure by a heat treatment procedure, such aswelding. Other mechanical means or other heat treatment procedures canalso be used to affix the engaging members to bumper structure.

FIG. 4 illustrates an obstruction removal device 300 according toanother embodiment of the present invention. The obstruction removaldevice 300 includes a proximal structure 301 connected to one or moreengaging members 303. There may be a distal structure 302 attached to adistal-most engaging member (labeled as 306 for clarity, though it maybe structurally the same or different as the other engaging members303). The one or more engaging members 303 are connected to the proximalstructure in such a way as to allow the one or more engaging members 303to rotate independently of the proximal structure 301. The one or moreengaging members 303 may be linked together to allow the engagingmembers 303 to rotate independently of each other as well, as discussedin more detail below. The obstruction removal device 300 is preferablypushed/pulled from one end of the proximal structure 301, thus the termsproximal portion structure and distal structure are used relative to thepushing/pulling end. Although five engaging members are illustrated inthe figure, fewer or more engaging members can be used. Like all of theembodiments described herein, the engaging members 303 are constructedwith one or more struts 101, as described above.

FIG. 5 illustrates an exploded view of an embodiment of the obstructionremoval device 300 of FIG. 4. The proximal structure 301 may include acore wire 307 which sits under a coil 309, which may sit under a tube310. The core wire 307 includes a flared end 308. The core wire 307 maybe made of nitinol, or a similar material, although other materials arewithin the scope of the invention. The coil 309 may be made of tantalum,or other radiopaque materials, although non-radiopaque materials mayalso be used. The tube 310 may be made of PET, or other polymericmaterial, although non-polymeric materials may be used as well. Theproximal structure also includes another coil 311 which is preferablymore gapped than coil 309, and can be made of a similar material. Coil311 sits between core wire 307 and the over-coil 309, and helps centercore wire 307 within coil 309. Proximal structure 301 is connected to aproximal engaging member 302, which can in turn be connected to anotherengaging member if more than one engaging member is used in theobstruction removal device.

The distal structure 302 includes a monofilament 315 which sits under acoil 316. Alternatively, multiple monofilaments can be bonded togetherto produce a monofilament structure 315. The monofilament 315 can bemade of a stretch-resistant polymer such as Engage, although othermaterials may be used. The coil 316 may be made of tantalum, or otherradiopaque materials, although non-radiopaque materials may also beused. Adhesive, preferably UV curable adhesive, 317 is used at both endsof the coil structure 316 in order to keep the monofilament 315 integralwithin the coil 316. In one example, the distal structure can act as aguidewire.

A distal structure 302 may be connected to the distal-most engagingmember 306. This distal structure may be radiopaque in order to aid inimaging of the device during deployment. In the embodiment of FIG. 5,the coil of the distal structure 302 fits within the hole 103 of thedistal-most engaging member 306, and a retaining piece 312 fits on theother end to keep the distal portion 302 integral with engaging member306. The retaining piece is welded within the interior of the structureof hole 103. The engaging member 306 can still rotate. The retainingpiece may be of a tubular construction, and may be made from nitinol,although similar materials can also be used. In order to aid in imaging,the retaining piece may be made from nitinol filled with a radiopaquematerial. Alternatively, the retaining piece may be coated with aradiopaque material to aid in imaging of the device during theprocedure. Alternatively, the retaining piece may be made of aradiopaque material.

The connection mechanism used to connect the engaging members togetheris shown in FIGS. 5 and 6. FIG. 6 illustrates the connection structureof engaging member 303, which is connected to the proximal structure 301of the obstruction removal device.

The connection mechanism includes a link 313 with two flared ends 314,and retaining pieces 312. The link 313 may be made of stainless steel,although similar materials may be used. The flared ends extend withinthe opposing holes 103, 104 of the engaging members being connected, andthe retaining piece 312 fits next to the flared end 314 to secure thelink 313 within the hole of the engaging member. This connectingstructure is used to connect the engaging members together, if more thanone engaging member is used in the obstruction removal device. Retainingpiece 312 is welded to the hole, and the link can rotate while securedwithin the hole of the engaging member. The engaging members mayindependently rotate.

Engaging member 303 is also connected to the proximal structure 301, asshown in FIGS. 5 and 6. The flared end 308 of the core wire sits pasthole 104 of engaging member 303 and a retaining piece 312 sits over thecore wire 307 to secure the proximal structure 301 to engaging member303, where retaining piece 312 is welded within hole 104. A smaller,gapped coil 311 sits within the distal end of coil 309 and serves tohelp center the core wire 307 within the coil 309.

In one example, the connecting piece 313 is placed within the holestructure, and retaining piece 312 is welded into the hole over theconnecting piece. The flared end 313 can subsequently be laser welded onthe end of the connecting piece. In another example, the retaining piece312 is welded into the hole and the connecting piece is placed within,and the flared end is laser welded. Although laser welding is specified,other similar heat treatment techniques can be utilized as well. Thisprocedure can also be utilized at the end of core wire 307 to produceflared end 308, and to connect proximal-most engaging member 303 to theproximal portion 301 of the device. In one example, this procedure canbe utilized at the end of the coil 316 when connecting the distalportion of the device to distal-most engaging member 306.

Each engaging member has a rotational component; this ability to rotatecan aid in capturing the thrombus and navigating the vessel. This canalso help limit the amount of endothelial denudation that may occur asthe device is being pushed and/or pulled through the vessel, by helpingto limit any excessive forces that build up due to excessive contactfriction between the struts and the vessel wall. The engaging membersmay also be configured to have a more rounded, smoother profile (asillustrated in the figures) which would eliminate any sharp edges on theengaging members which may otherwise promote denudation due to highcontact friction. Furthermore, due to the space between the engagingmembers, less material physically contacts the vessel than other designswhich may utilize, for example, a longer one-piece clot engaging unit.Less material contacting the vessel will also serve to limit endothelialdenudation during the clot removal procedure.

In one example, the proximal portion 301 of the obstruction removaldevice can include means to detach the engaging members from theobstruction removal device. The detachment means can be included on theportion of the proximal portion 301 contacting engaging member 303 (theproximal-most engaging member) and can include electrolytic, mechanical,thermal, or other means known in the art to induce severing and/ordegradation of a linkage.

One or more of the engaging members may actively engage the clot, whileother members can be positioned either distally beyond, or proximallybefore, the thrombus—depending on the size of the clot and the number ofengaging members utilized on the device. Due to the potentialvariability in the individual shape and/or profile of each engagingmember, as well as the number of engaging members used in theobstruction removal device compared to the size of the clot, one or moreengaging members may sit distally past the clot and have a denser cellconfiguration to act as a filter for catching thrombus that may dislodgewhen capturing the clot utilizing the obstruction removal device.

The engaging member(s) which act as a filter may have a meshconfiguration; said mesh configuration can be throughout the wholeengaging member or be located on one particular side of the engagingmember, in order to maximize the chances of catching loose thrombuswithout the thrombus dislodging. In one example, the engaging member(s)which act as a filter has a denser cell configuration on the more-distalportion of said member in order to catch thrombus dislodged frominteraction of the more proximal engaging members with the clot. Thisarrangement can be useful when the more proximal engaging membersinteract with the clot and portions of the clot macerate. The moredistal engaging members with the filter configuration can catchmacerated thrombus that otherwise might accumulate in the bloodstream.The engaging members which act as a filter may be formed from nitinol,stainless steel, or similar materials.

Alternatively, they may be formed from laser cut polymers.Alternatively, these engaging members acting as filters may have aninverted braid configuration, or other basket-type configurations, orother configurations known within the embolic protection device art. Oneor more of the engaging members may also be composed of a thrombogenicmaterial, or may be coated with a thrombogenic material in order to aidin the clot retrieval procedure, by promoting adhesion between theengaging member and the thrombus. Alternatively, an anti-thrombogenicmaterial can be used, or an anti-thrombogenic coasting can be used inorder to help dissolve a portion of the clot that is in contact with theengaging members. This can be useful with, for instance, retrievaloperations involving a large clot.

FIGS. 7 and 8 illustrate another embodiment of the obstruction removaldevice utilizing one or more engaging members which act as a filter inorder to catch thrombus that may become dislodged during the clotremoval procedure. FIG. 7 illustrates the obstruction removal device,with a proximal portion 401 and distal portion 402. The proximal portionincludes engaging members 303. The distal portion includes engagingmembers 407 and 408. The distal engaging members 407 and 408 have adenser cell configuration to act as a filter to trap dislodged thrombuswhich may shear off during the clot removal procedure, the clot removalprocedure being generally described above. The denser cell configurationis due to an inner and outer structure used to form the engaging member,as illustrated in FIG. 8.

As illustrated in FIG. 8, the two distal engaging members 407 and 408are each composed of an inner structure 409 and outer structure 410,where the inner structure may nest within the outer structure. The innerstructure 409 and outer structure 410 which comprise the distal engagingmembers 407 and 408 may be made from laser cut nitinol, or a similarmaterial. The proximal portion 401 and distal portion 402 are configuredthe same as the embodiment presented in FIGS. 4-5, as are the linkagesbetween each of the engaging members, although this filtering engagingmember structure can be applied to any of the engaging members presentedin any of the presented obstruction removal device embodiments.

The cell pattern may be slightly offset on the inner and outer structurein order to create a denser cell profile when the inner structure isnested within the outer structure. As shown in FIG. 9, the distal part510 of the engaging member 408 has a denser cell profile than theproximal part 511 in order to catch dislocated thrombus which may escapeduring the clot removal procedure. This arrangement can be useful whenthe more proximal engaging members interact with the clot and portionsof the clot macerate. The more distal engaging members with the filterconfiguration can catch macerated thrombus that otherwise mightaccumulate in the bloodstream. Although FIGS. 7 and 8 illustrate twoengaging members having the inner and outer structure to act as afilter, more or fewer engaging members can have this filter structure.

In one embodiment for delivery of the device described in the previousembodiments, an obstruction removal device is sheathed within a deliverydevice, and the delivery device is delivered through a catheter. In oneexample, the delivery device can be a microcatheter. The delivery deviceis delivered to the site of the obstruction and then pulled back.Pulling back the delivery device unsheathes the obstruction removaldevice, such that the engaging members expand upon retraction of thedelivery device.

Alternatively, the obstruction removal device is pushed out of thedelivery device, which subsequently allows the engaging members toexpand. Depending on the number of engaging members on the obstructionremoval device, the size of the clot, and the location of deliveryrelative to the obstruction, some members may sit distally past, and/orproximally before, the obstruction. The obstruction removal device maybe maneuverable via the core wire. Once the obstruction removal deviceengages the obstruction, the delivery device can be withdrawn to a pointjust past the distal end of the catheter, and then the catheter can bewithdrawn. Alternatively, the obstruction removal device can bewithdrawn from the vasculature by withdrawing the delivery device intothe catheter, and subsequently withdrawing the catheter, or withdrawingthe delivery device and/or obstruction removal device through thecatheter. Alternatively, the catheter can be withdrawn wholly to removethe delivery device and obstruction removal device. In another example,the delivery device can be a hypotube.

In an alternative embodiment, the device may be delivered directlythrough the catheter, without being sheathed in a delivery device.

FIGS. 10-12 illustrate an example of a particular method for deployingthe obstruction removal device. In this example, the delivery device 602is delivered through the vasculature 600 to the site of the clot 601.The obstruction removal device 603 is pushed through the delivery deviceto the site of the clot. Although this particular example illustratesthe obstruction removal device deployed in the middle of the clot, thedevice may be deployed within the clot, or in a location proximal ordistal relative to the clot location. Some engaging members may sitdistally past and/or proximally before the clot, depending on the sizeof the clot and the number of engaging members used on the obstructionremoval device. Delivery device 602 is then retracted which allows theengaging members of the obstruction removal device to expand andinteract with portions of the clot. The obstruction removal device 603can be manipulated by the operator from the proximal portion 604 of thedevice. Once the obstruction removal device has secured the clot, thedevice can be withdrawn as described above. Aspiration may also be usedto aid in the clot/obstruction removal procedure. FIGS. 10-12 illustratea particular example for illustrative purposes. Other delivery methodsare contemplated within the scope of the invention, such as pushing theobstruction removal device from the delivery device.

The engaging members may all be the same size, may all be differentsizes, or may have some engaging members sized differently from others.In one example, the diameter range for spherically shaped engagingmembers may be between 1-12 millimeters. In another example, a diameterrange of 3-6 millimeters is used.

The engaging members are formed from a hypotube which is laser-cut intoa particular pattern based on the shape of the struts 101 and cells 102.This hypotube 700 is shown in FIG. 13. The hypotube is heat treated, inone example the hypotube can be heat set at 530-550 degrees Celsius for5 minutes. The hypotube is subsequently quenched in water to cool. Anexpansion plunger 702 is then inserted and used to expand a portion ofthe hypotube (see FIG. 14). The expanded hypotube is then heat-set tothis expanded shape. In one example, it is heat set at 530-550 degreesCelsius for 3 minutes. The expanded hypotube is subsequently quenched inwater. Based on the size of the engaging member, the expansion plungerand subsequent heat treatment step can be used on multiple portions ofthe engaging member, where each section is heat set after expansion. Anexpansion pin 704 is subsequently inserted within the hypotube to helpexpand the walls of the hypotube (see FIG. 15). The expanded hypotube700 is placed in a fixture. The fixture includes two plates 706, 708.Threaded rods connect the plates, and the plates have an externalmounted nut. The nut can be tightened to compress the plates together inorder to further expand the hypotube. Once the appropriate shape is set,the expanded hypotube can be heat treated (in one example, heat treatedat 530-550 degrees Celsius for 5 minutes) and quenched to set the shapeof the engaging member.

The engaging members are subsequently pickled, etched, andelectropolished to set the final shape of the said members. Theobstruction removal device is then assembled together with the one ormore engaging members. Though the engaging members are heat-set andtreated into an expanded shape, they still retain a high degree of shapememory due to factors such as material properties and strut thickness.Thus, the engaging members will adopt an expanded shape when notrestrained (i.e. not sheathed in a delivery device) and will adopt acontracted shape similar to the initial hypotube shape when restrained(i.e. sheathed in a delivery device).

In several previously presented embodiments of the obstruction removaldevice, the engaging members are self-expandable when released from adelivery device (e.g. microcatheter) and self-collapsible when housedwithin the delivery device. In some embodiments and scenarios, it wouldbe useful to have a locking feature to lock one or more engaging membersin an expanded and/or collapsed configuration. Neurovascular bloodvessels are small and tortuous. When an obstruction removal device andassociated engaging members are used to remove a clot in theneurovasculature, the geometry of the blood vessels can prevent theengaging members from fully opening, or can cause the engaging membersto prematurely collapse after the clot has been retained while thedevice is being retracted through the vasculature for evacuation out ofthe patient vasculature. A locking functionality which would lock theengaging members in an expanded shape would address these issues.

For the purposes of the figures which will now be discussed, unlessindicated otherwise, anything to the left side in the figures isconsidered distal (or in the direction of further placement within thevasculature) while anything to the right is considered proximal (or inthe direction of where vessel access was obtained).

FIG. 17 shows an obstruction removal device 800 that is generallysimilar to the previously described embodiments, but further includes amechanism for manipulating or otherwise maintaining the shape of itsengaging members 802 a-802 d in an expanded position. The device 800includes a number of engaging members 802 a-802 d (e.g., 4 members) thatare connected to each other to form a linear shape. The proximal-mostengaging member 802 d is connected to a distal end of an elongatedpusher 806.

The manipulating mechanism is controlled by a shape controller member808 that connects at a distal end of the distal engaging member 802 d,extends through each of the engaging members 802 a-802 d, through apassage in the pusher 806, and terminates at or near a proximal end ofthe pusher 806. In this respect, a physician can pull on the shapecontroller member 808 and pull the engaging members 802 a-802 d againstthe distal end of the pusher 806, thereby maintaining them in theirexpanded configuration.

The pusher is preferably an elongated body having a diameter suitablefor passing within a catheter or sheath, and further includes a lumen orpassage therein to accommodate the shape controller 808. Similar to theprevious embodiment best shown in FIG. 1, each of the engaging members802 a-802 d include proximal and distal apertures 103 and 104 that arealigned with each other along a longitudinal axis of the device 800 andin line with the passage of the pusher 806. Additionally, each engagingmember 802 a-802 d also includes tubular elements 804 a-804 d (e.g., ametal hypotube), that are only connected to the distal or “left” end ofeach engaging member (or alternately the proximal end of each engagingmember), but not to the opposing side of the engaging members 802 a-802d. The tubular elements 804 a-804 d are each aligned so their internalpassage connects between the proximal and distal apertures of each ofthe engaging members 802 a-802 d. In this respect, a passage is createdthrough the pusher, engaging members 802 a-802 d, and tubular elements804 a-804 d. A variety of techniques including adhesives, soldering, ormechanical screw can be used to connect the tubular elements 804 a-804 dto the engaging members 802 a-802 d.

The shape controller 808 passes through this passage, including throughthe lumen of the pusher, the engaging members 802 a-802 d, and thetubular elements 804 a-804 d. A distal end of the shape controller 808is attached to a distal cap 810 at the distal end of the distal-mostengaging member 802 a. Again, adhesives, welding, or mechanical screwconcepts can be used to make this attachment and preferably the cap 810has a diameter larger than that of the distal aperture of distalengaging member 802 d. Alternatively, shape controller 808 can bemechanically attached directly to the distal end of distal engagingmember 802 a.

Shape controller 808 is separately movable from pusher 806 since thecontroller is located within the pusher's lumen, such that the user canindependently and separately longitudinally move the controller 808relative to the pusher 806. While the pusher 806 is used to control theposition of the entire obstruction removal device including theattached/associated engaging members 802 a-802 d, the controller 808 isused to control the shape of the engaging members 802 a-802 d.Preferably, the shape controller 808 is a wire, a flexible rod, orsimilar elongated element having a length that extends between thedistal end of the device and at least to the device's proximal end.

Since the shape controller 808 is connected to the distal cap 810,pushing the controller 808 creates distal force against cap 810 (or thedistal end of distal engaging member 802 a if no such cap is used).Since the tubular elements 804 a-804 d are fixed only to the left ordistal side of the engaging members, the tubular elements 804 a-804 drelease from contact with the proximal end of the engaging members—asshown in FIG. 18 and move distally as the engaging members 802 a-802 dbecome increasing oval and/or elongated. Conversely, pulling orretracting the controller 808 exerts an opposite, proximal force againstcap 810 (or distal engaging member 802 a, if no cap is used) such thatthe engaging members 802 a-802 d radially expand to a spherical shapeuntil the floating or proximal end of the tubular elements 804 a-804 dcontact the internal, proximal surface of the engaging member, therebypreventing any further expansion by the engaging members 802 a-802 d orfurther proximal movement by the shape controller 808. In this respect,the attached tubular elements 804 a-804 d serve to resist overlyexpanding the engaging members 802 a-802 d. In one embodiment, thetubular elements 804 a-804 d are attached to only one end of engagingmembers 802 a-802 d (e.g., the left or distal end of said engagingmembers), and that particular attached end may be composed of a dense,weighted material that therefore provides some resistance to movement inthat particular direction. For example, where the tubular elements 804a-804 d are attached to the distal end of the engaging members 802 a-802d, the distal end of each engaging member will be weighted and naturallyresist natural forces based on movement through the vasculature whichcould cause said engaging members to collapse. Therefore, even inscenarios where the user has not used the shape controller to expand orcollapse the engaging member, the presence of the tubular elements canstill cause the engaging members to naturally resist a change in shape.

During use within a patient, the shape controller 808 can be used toprevent the collapse of the engaging members 802 a-802 d, especiallythrough curved or tortuous regions. However, the user also has theability to collapse the engaging members 802 a-802 d, which may bedesirable during withdrawal of the device 800 (e.g., into a sheath orcatheter).

In one embodiment, the controller 808 includes a collet or other lockingmechanism at its proximal end so that the user can lock the controller'sposition relative to the pusher 806, which will also lock the engagingmember shape. Other embodiments can forego the locking mechanism andinstead rely on the user to apply force to the controller 808 tomanipulate the engaging members 802 a-802 d to adopt and maintain acertain shape.

FIG. 19 shows an alternative embodiment of the device 801 that isgenerally similar to the previously described device 800. However, thetubular elements 804 a-804 d are instead affixed to the proximal (orright) end of the engaging members 802 a-802 d, instead of the distal(or left) end of the engaging members 802 a-802 d as shown in FIG. 18.In this embodiment, pushing the controller 808 still causes the engagingmembers 802 a-802 d to collapse while pulling the controller 808 stillcauses the engaging members to expand.

In one example, the pusher tube 806 is a tapered nitinol hypotube withdimensions of about 0.004 inch inner diameter and about 0.015 inch outerdiameter and shape controller 808 is a wire of about 0.003 inch outerdiameter. The wire can be made of a variety of materials includingmetals, fibers, and polymers such as nitinol, stainless steel, Vectran,Kevlar, PET, polypropylene. These sizes can be increased or decreasedbased on the size of the obstruction removal device and these sizes areonly offered as an example. Shape controller 808 can also take the formof a wire, hypotube, or other elements. The proximal end of shapecontroller 808 can also include a handle or similar user interface toallow easier handling by the user.

In one embodiment, tubular elements 804 a-804 d are radiopaque to aid inimaging. Radiopaque material such as platinum, tantalum, palladium, orgold can be used. The imaging may be useful so the physician candetermine whether the engaging members are collapsed or expanded basedon the relative position of the tubular elements to each other. As shownin FIGS. 18-19, when the engaging members are collapsed, the tubularelements 804 a-804 d take on a spaced-apart, gapped configuration.Utilizing imaging technology where the tubular elements are radiopaque,the physician can see the gapped tubular element configuration shown inFIG. 20 which will confirm that the engaging members are collapsed. Incontrast, when the engaging members are expanded (as shown in FIG. 17),tubular elements 804 a-804 d are relatively close together in acontinuous line as shown in FIG. 21, confirming that the engagingmembers are expanded. In this manner, a physician can use imaging toconfirm whether the engaging members are collapsed or expanded.

Other embodiments can utilize a coil element instead of tubular elements804 a-804 d which spans the entire length of each engaging member 802a-802 d. The advantage of a coil element is that it can be attached toboth ends of the engaging member, where the ability of the coil tostretch will allow the engaging member to collapse or expand.Alternatively, the coil element can be used like the tubular elements804 a-804 d of FIGS. 17-21, where one end of the coil is affixed to theengaging member 802 a-802 d while the other end is free.

As discussed earlier, the presence of the coil or tubular element isbeneficial since it naturally resists collapse of the engaging members.The coil or hypotube can therefore be seen as tensioning members whichhelp to resist collapse of the engaging members. However, one embodimentcould forego the coil or tubular element, and instead utilize controller808 as the sole mechanism to control the shape of the engaging elements.This embodiment allows the user to control the engaging member shapealthough there is no “stop” mechanism to prevent the engaging membersfrom being excessively radially expanded by the shape controller 808.

FIGS. 22a, 22b , and 23 illustrate a device 803 that is generallysimilar to the previously described embodiments 800 and 801. However,rather than relying on the user to maintain the shape controller'sposition or a separate collet mechanism to lock shape controller 808(and therefore engaging elements 802 a-802 d in a particular shape),controller 808 includes a locking element 812 which can mate with orlatch onto a portion of the engaging members to lock the engaging memberin a particular shape.

Like the embodiments of FIGS. 17-21, this system utilizes a proximalpusher 806 and a shape controller 808 channeled through the pusher 806and exiting the distal end of the pusher to span through the alignedengaging members 802 a-802 d. Controller 808 includes a plurality offixtures, configured as star-shaped holder members 812 a-812 d (e.g., 4)that are each fixed to the controller within an engaging member 802a-802 d (i.e., each engaging member has a holder within it). Shapecontroller 808 is distally connected to either a distal cap element oris connected to the distal-most engaging member 802 a so that pushingcontroller 808 will cause the engaging members to collapse while pullingcontroller 808 will cause the engaging members to expand. Since theholder members 812 a-812 d are fixed to the controller, displacement ofshape controller 808 will also displace said holders. In this respect,the holder members provide a backstop mechanism, limiting how far thecontroller 808 can be proximally withdrawn and therefore also limitingthe shape and radial expansion of the engaging member 802 a-802 d.

The star-shaped holder members 812 a-812 d, shown in detail in FIG. 22b, contain a passage 815 through which the shape controller 808 ispositioned. Mechanical means such as welding or adhesive can be used toconnect the holder to the controller, or alternatively, the holdermembers can be formed integrally onto the shape controller 808. Theholder members include a plurality of curved, radial recesses,depressions, or slots 816, which contribute to the general star-likeshape of the holder elements. Additionally, the holder members 812include a tapered proximal surface and a flat distal surface. Since theholder members 812 a-812 d are located on the shape controller 808,retracting or pulling the controller will also displace the holdermembers 812, allowing them to engage the proximal struts of theirdedicated engaging member 812. The recesses 816 of the holders are sizedto engage or partially capture the engaging member struts. Therefore,pulling the controller 808 will cause the holder members 812 a-812 d tocontact the engaging member struts, and the struts will be retained inthe slots/recesses 816 of the holder members 812. The holder members 816can be made of a variety of materials including nitinol, stainlesssteel, polymers, or radiopaque materials such as tantalum, platinum,palladium, or gold.

The recesses 816 can be either larger in width than the struts orslightly oversized relative to the size of the struts in order todirectly accommodate said struts. Alternatively, slots/recesses 816 cancontain a tapered, conical, proximal surface that has a generallysimilar, but inverted, curvature as the interior of the engaging members812 that allows the two surfaces to mate together.

The device 803 can be configured so that the strut-lock functionality iseither permanent or temporary. For example, in a permanent-lock designthe struts are locked with the holder member permanently and thecontroller 808 would therefore also be locked. In animpermanent/temporary lock design, the user exerts sufficient force(e.g., by pushing the controller 808 with sufficient force to overcomethe locking force) to free the struts from the recesses 816 of theholder member 812 to unlock the system.

When shape controller 808 is pulled proximally, holder members 812 a-812d will engage the engaging member's 802 a-802 d proximal struts (orrightwards, from the vantage point of the figures) to lock the engagingmembers in an expanded configuration, as shown in FIG. 23. Thisfunctionality can also be used to lock the engaging members in acollapsed state, where pushing controller 808 will cause the holdermembers to engage the distal (or leftwards, from the vantage point ofthe figures) struts, collapsing the engaging members. The proximal anddistal strut configuration, best seen in FIG. 1, is arranged in a flowerbulb petal-type shape with five strut regions 101 emanating from holes103/104. The holder members 812 also contain five recessed regions 816,where each recess corresponds to one strut region. Other embodiments canutilize different strut patterns and a different number of recesses 816to accommodate the different strut pattern.

Please note, previous embodiments of the engaging members included thosewhere the engaging members sit along a common core member (e.g., FIG. 3)and those where separate link elements link together pairs of engagingmembers (e.g. FIGS. 5-6). Either embodiment can be used along with thelocking or shape changing functionality discussed with regard to theshape controller 808. Where a common core member (e.g. as shown in FIG.3) is used to span all the engaging members, controller 808 may be usedin place of the larger tubular structure shown or the controller couldtake on the form of the common tubular core structure shown on which thevarious engaging members are placed. Where separate link elements 313are used to link pairs of engaging members together (e.g. as shown inFIG. 5), each link element 313 can utilize a lumen which accommodatesshape controller 808.

Other embodiments can utilize a holder member that is positioned onlypartially around the shape controller (for instance, taking only the topportion or bottom portion of holders 812 a-812 d) where the holder onlyengages some of the struts. Additional embodiments can utilize only oneholder, for instance a distal holder which locks the distal engagingmember, or a proximal holder which locks the proximal engaging member.Though multiple holders augment the locking force on each engagingmember, a one holder embodiment would simplify the locking operationwhile still applying some locking force to the plurality of engagingmembers.

In one embodiment, both collapsed and expanded locking are possible suchthat the engaging members can be locked in both an expanded and acollapsed state. In another embodiment, only collapsed locking ispossible. In another embodiment only expanded locking is possible. Thelocking possibilities can be controlled based various variablesincluding the location of the holders 812 a-812 d within each engagingelement 802 a-802 d, size of each holder, and the overall displacementof shape controller 808. In one embodiment, a collet lock mechanism atthe proximal part of shape controller 808 could also be used along withthe holder concept in order to further augment the locking force whichlocks the engaging members.

FIGS. 24a and 24b show another embodiment of a thrombus removal deviceutilizing a shape controller 808 similar to those described in previousembodiments, but using a different locking mechanism to maintain theposition of the shape controller 808. Specifically, one or moreenlargements 818 can be included on the shape controller 808 that engageor enter a channel 820 (e.g., an aperture, groove, or recess) in atubular pusher 806, thereby locking the shape controller 808 in itslongitudinal position. Preferably, the area of the lumen opposite andadjacent to the channel 818 is shaped to help urge or direct theenlargement 818 into the channel 820, such as a ramped surface or bulge.While one channel 820 is shown, two channels are possible, positionedsuch that the locking or detent position maintains the engaging member802 in either the collapsed or expanded positions.

Similar to the other embodiments, shape controller 808 is connected tothe distal-most engaging member (or alternatively, a distal end cap)such that pulling the controller will cause the engaging members 802 toexpand while pushing the controller will cause the engaging members 802to collapse. To lock the engaging members in an expanded configuration,the user pulls or pushes the controller 808 such that enlargement 818reaches channel 820 and moves into the channel, thereby locking theposition of the engaging members.

FIGS. 25a and 25b illustrate an alternative locking embodiment in whichno channel is used. Instead, the enlargement 118 is composed of asomewhat malleable material such that it can be pinched to fit withinthe distal end of the pusher tube, but where further retraction of theenlargement is not possible. Optionally, the enlargement may have adistally decreasing taper to further facilitate entry into the pusher806 but also prevent retraction. The internal lumen of the pusher 806can also be tapered such that its distal end is slightly larger than themore proximal section, thereby preventing enlargement 818 from proximalmovement beyond a certain point and therefore retaining theconfiguration of the enlargement 818. In one embodiment, once theengaging members 802 are locked, this configuration is permanent. Inanother embodiment, the user can apply sufficient force to remove theenlargement 818 from the retention structure to unlock the position ofthe engaging members.

While the embodiment just described functions only to lock the engagingmembers in an expanded configuration, other embodiments can also orinstead utilize a distal tubular structure to lock the engaging membersin a collapsed configuration. In these embodiments, a distal tube (e.g.similar to distal tubular structure 302 in FIG. 5) is connected to thedistal end of the distal-most engaging member and this tubular structureutilizes the same retention mechanism of FIGS. 24-25 to lock anenlargement along shape controller 808. In this way, the engagingmembers can be locked either in an expanded or a collapsedconfiguration. Alternative embodiments can solely utilize this distalretention structure such that the engaging members can only be locked ina collapsed state.

This embodiment can be used within the linking structures 313 (see FIG.5) in those embodiments where the engaging member pairs are linked viathe linking structures. In this embodiment, the linking structures 313also utilize the configurations of FIGS. 24-25 and there are multipleenlargements 818 along controller 808 (e.g. 4 engaging members, and 4enlargements in which each enlargement serves to lock the engagingmember). The shape controller 808 is pushed/pulled so that theenlargements 818 mate with the locking structure to lock the expandedand/or collapsed configuration of the engaging members. Multiple lockingstructures would further augment the locking strength keeping theengaging members in a particular shape, but would also increase thecomplexity of the locking mechanism. The advantage of one lockingstructure (either located on the pusher 806 or on the distal tubularstructure connected to the distal or furthest engaging member) is thatone locking structure could be used to lock multiple engaging members,while potentially allowing the user to unlock the engaging members byapplying sufficient force. Generally, in most scenarios it would bebeneficial for a user to be able to selectively lock or unlock theengaging member shape—for instance to lock the engaging members in anexpanded shape to aid in clot retention, but later unlock the engagingmembers to allow said engaging members to collapse into a sheath forretraction out of the vasculature once the clot/obstruction removalprocedure is complete.

In another embodiment, the locking mechanism is calibrated such that theoperator can use the diameter of the blood vessel to determine theappropriate diameter of the engaging members and lock the engagingmembers to the appropriate diameter. In this way, the operator is ableto change the diameter based on the changing anatomy (e.g. as the devicecomes from the smaller diameter M2 segment of the Middle Cerebral Arteryto the larger diameter M1 segment, the operator has the option of‘fixing’ the device in a greater diameter corresponding to the increasedsize of the M1 compared to M2 segment).

In another embodiment, the locking mechanism is designed to allowvariable resistance at the choice of the operator. If the operator feltthat the resistance is too high while retrieving the obstruction removaldevice, he or she could transiently ‘relax’ the locking mechanism toallow more flexibility and reduced resistance in the engaging members.For instance, the locking mechanism may have a degree of freedom or“give” to lower the resistance while still locking the engaging membersin an expanded and/or collapsed shape.

In an alternative embodiment, the device mentioned in the previousembodiments can be used to retrieve foreign objects, in addition toclots or other obstructions. Circumstances may arise where foreignobjects, such as embolic coils normally used to fill an aneurysm, maybreak off or otherwise become detached within the vasculature. Thedevice can be used to retrieve the foreign body utilizing a proceduresimilar to the procedure used during obstruction removal.

While prior embodiments have disclosed various mechanism to lock theshape controller in a longitudinal position, it should be understoodthat the term locking mechanism can, in some circumstances, beinterpreted to also include the shape controller and one or more of thedistal structures fixed to the distal end of the shape controller tocontact/engage the engaging members.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

1. An obstruction removal device comprising: a pusher having a pusherlumen extending between a distal end of the pusher and a proximal end ofthe pusher; one or more engaging members connected to the pusher andconfigured to capture a thrombus within a vasculature; an elongatedelement positioned in the pusher lumen and extending from the distal endof the pusher and being connected to at least one engaging member of theone or more engaging members; the elongated element longitudinallymoveable relative to the pusher so as to cause at least one engagingmember of the one or more engaging members to adopt an expanded orcollapsed shape; and a locking mechanism selectively preventing theelongated element from moving relative to the pusher and thereby lockingat least one engaging member of the one or more engaging members in atleast one of the expanded or the collapsed shape; wherein the lockingmechanism comprises a fixture fixed to the elongated element andpositioned within at least one engaging member of the one or moreengaging members; the fixture having a plurality of recesses adapted toalign and engage a plurality of struts of the at least one engagingmember.
 2. The obstruction removal device of claim 1, wherein theelongated element extends beyond the proximal end of the pusher.
 3. Theobstruction removal device of claim 1, wherein the elongated elementspans both the pusher and the one or more engaging members.
 4. Theobstruction removal device of claim 1, wherein each of the plurality ofrecesses engages one of the plurality of struts.
 5. The obstructionremoval device of claim 1, wherein the fixture is star-shaped.
 6. Theobstruction removal device of claim 1, further comprising a colletlocated near the proximal end of the pusher and being selectivelyengageable with the elongated element to prevent movement of theelongated element relative to the pusher.
 7. The obstruction removaldevice of claim 1, wherein the one or more engaging members comprise twoor more engaging members.
 8. The obstruction removal device of claim 1,wherein the one or more engaging members comprise a plurality ofengaging members, and the at least one of the one or more engagingmembers comprises all of the plurality of engaging members.
 9. Anobstruction removal device comprising: a pusher having a pusher lumenextending between a distal end of the pusher and a proximal end of thepusher; one or more engaging members connected to the pusher andconfigured to capture a thrombus within a vasculature; an elongatedelement positioned in the pusher lumen and extending from the distal endof the pusher and being connected to at least one engaging member of theone or more engaging members; the elongated element longitudinallymoveable relative to the pusher so as to cause the at least one engagingmember of the one or more engaging members to adopt an expanded orcollapsed shape; and a locking mechanism selectively preventing theelongated element from moving relative to the pusher and thereby lockingthe at least one engaging member of the one or more engaging members inat least one of the expanded or the collapsed shape; wherein the lockingmechanism includes a structure mounted over the elongated element andconfigured to contact the at least one engaging member of the one ormore engaging members.
 10. The obstruction removal device of claim 9,wherein the one or more engaging members comprise a plurality ofengaging members.
 11. The obstruction removal device of claim 10,wherein the locking mechanism locks at least two engaging members of theplurality of engaging members in at least one of the expanded or thecollapsed shape.
 12. The obstruction removal device of claim 10, whereinthe structure is a tube positioned over the elongate element.
 13. Theobstruction removal device of claim 10, wherein the elongated elementspans all of the plurality of engaging members.
 14. The obstructionremoval device of claim 10, further comprising a collet located near theproximal end of the pusher and being selectively engageable with theelongated element to prevent movement of the elongated element relativeto the pusher.
 15. The obstruction removal device of claim 10, where thelocking mechanism locks all of the plurality of engaging members in atleast one of the expanded or the collapsed shape.
 16. The obstructionremoval device of claim 15, wherein each of the plurality of engagingmembers has its own dedicated structure.
 17. An obstruction removaldevice comprising: a pusher having a pusher lumen extending between adistal end of the pusher and a proximal end of the pusher; one or moreengaging members connected to the pusher and configured to capture athrombus within a vasculature; an elongated element positioned in thepusher lumen and extending from the distal end of the pusher and beingconnected to at least one engaging member of the one or more engagingmembers; the elongated element longitudinally moveable relative to thepusher so as to cause at least one engaging member of the one or moreengaging members to adopt an expanded or collapsed shape; and a lockingmechanism selectively preventing the elongated element from movingrelative to the pusher and thereby locking at least one engaging memberof the one or more engaging members in at least one of the expanded orthe collapsed shape; wherein the locking mechanism comprises a region ofenlarged diameter on the elongated element and an opening in the pushertube sized to capture the region of enlarged diameter.
 18. Theobstruction removal device of claim 17, further comprising a colletlocated near the proximal end of the pusher tube and being selectivelyengageable with the elongated element to prevent movement of theelongated element relative to the pusher tube.
 19. The obstructionremoval device of claim 17, wherein the one or more engaging memberscomprise a plurality of engaging members.
 20. The obstruction removaldevice of claim 19, wherein the locking mechanism locks all of theplurality of engaging members in at least one of the expanded or thecollapsed state.